The present subject matter generally concerns the detection of anomalies in and/or properties relating to a pneumatic tire using Doppler radar technology. More particularly, the present disclosure relates to methods and apparatus for the detection of anomalies in pneumatic tires including, but not limited to, tread separation, tread wear, uneven tread wear, tire balance and foreign body detection using Doppler Micro-Power Impulse Radar (MIR).
Tread belt separation in pneumatic tires is a known, and potentially dangerous, problem. Tires that are under-inflated, overloaded, and driven in hot climates can undergo tread belt separation. Tread belt separation may also be associated with improperly manufactured, or improperly re-manufactured, (i.e., so called, re-capped) tires. Tread belt separation can have significantly negative results on the vehicle operation should, the tread separate from a pneumatic tire while in service and at highway speeds. The present technology describes apparatus and methodology for detecting this and other conditions so that the driver can be alerted to these conditions.
Previous efforts have been made to monitor tires during use in an effort to detect actual or imminent failure and to warn drivers of such actual or imminent failure so that cautionary measures may be taken. One such effort is described in U.S. Pat. No. 5,436,612 (Aduddell) and involves the placement of plural microphones and radio transmitters at various locations on a truck. The transmitters broadcast sounds detected by the various microphones to a receiver positioned with the driver. In this way a driver could listen for any anomalous sound and, if heard, take appropriate measures.
U.S. Pat. No. 6,255,940 (Phelan et al.) describes a patch that may be installed inside a tire by attachment to the innerliner of the tire. The patch supports sensors that monitor tire temperature and pressure. A warning may be given to the vehicle driver upon sensing abnormal conditions. Another tire temperature monitoring technique is disclosed in U.S. Pat. No. 4,570,152 (Melton et al.). In this patent, a number of permanent magnets are implanted into the tire body. Excess heat generated from the running of the tire will cause variations in the magnetic field of the permanent magnets. These variations are detected and used to generate a warning to the vehicle driver.
Yet another previously known technique for monitoring tires and, in particular, used for monitoring for tread separation is taught by U.S. Pat. No. 6,028,508 (Mason). Mason '508 discloses a system employing a ranging system wherein a sensor using a transmitter and receiver combination is employed to detect the distance from the sensor to the surface of a tire being monitored. The arrangement is such that an alarm is issued if the distance from the sensor to the surface of the tire exceeded a predetermined amount.
Yet another previously know technique for monitoring pneumatic tires is taught in U.S. patent application Publication US 2002/0189336 A1 (McEwan). McEwan discloses placement of radar sensors at various positions relative to a pneumatic tire to monitor for different types of tire anomalies. McEwan, for example, discloses detection of tread loss by positioning a radar unit to illuminate a tangential portion of the tire tread such that, upon loss of tread, there would be a substantial, detectable reduction in returned radar signal. McEwan also discloses detection of foreign bodies penetrating the tire tread by positioning the radar unit to illuminate a tangential portion of the tire and examining radar return signals by comparing the average amplitude to a peak amplitude. Other tire related properties or anomalies are detected by positioning the radar unit variously, for example, side wall properties my be examined by positioning the radar unit to illuminate the side wall and speed of rotation may be examined by positioning the radar unit to illuminate, for example, spokes or openings in the wheel on which a tire may be mounted.
While various aspects and alternative features are known in the field of tire failure and protection technology, no one design has emerged that generally integrates all of the ideal features and performance characteristics as discussed herein.
An exemplary background reference in addition to those already cited in the specification includes the January/February 1996 publication by Science & Technology Review entitled “Micropower Impulse Radar.” The disclosures of all the foregoing United States patents are hereby fully incorporated into this application by reference thereto.